1. Field of the Invention
The present invention relates to a vehicle-carried unit for automatic toll-paying systems, and an automatic toll-receiving apparatus, and in particular relates to a vehicle-carried unit for automatic toll-paying systems carried on a vehicle for automatically paying a toll through communication with an on-road unit, and an automatic toll-receiving apparatus for automatically receiving a toll through communication between a vehicle-carried unit and an on-road unit on a toll road such as an expressway.
2. Description of the Prior Art
An automatic toll-paying system, which utilizes a recording medium (for example, a card) of a prepaid system, has been hitherto developed for paying charges for utilization of pay facilities, for example, for paying a toll for passage over a toll road. In such a prepaid system, a prepaid amount of money is recorded beforehand on a recording medium, and every time a toll road is utilized, a toll for passage is subtracted from the amount of money recorded on the recording medium through wireless communication at a tollbooth gate at an entrance or an exit, and a balance is recorded on the recording medium.
However, in the case of such an automatic toll-paying system, if a balance recorded on the recording medium is not enough for a necessary amount of money such as for a toll for passage, it becomes difficult to pay the toll by using the recording medium, and complicated operations become necessary such that a shortage amount must be paid in cash.
In order to solve the problem described above, Japanese Patent Laid-open No. 5-012289 discloses a technique in which incremental data is transmitted to a wireless card in accordance with an invested amount of money for use with the card. Further, Japanese Patent Laid-open No. 5-217042 discloses a technique in which the balance of a card is updated through wireless communication in accordance with a presented amount of money at a tollbooth on a traffic lane. Furthermore, Japanese Patent Laid-open No. 5-210687 discloses a technique in which a certificate of utilization record of a card is issued on the basis of user information.
Techniques relevant to the present invention include techniques described in Japanese Patent Laid-open Nos. 62-098482, 4-255090 and 5-012521.
However, the techniques described in Japanese Patent Laid-open Nos. 5-012289 and 5-217042 have a problem, wherein it is necessary to go to a predetermined place such as a tollbooth and a service area to update the balance of a card, and hence it is postulated that the place may be crowded. Even if a plurality of cards are possessed, and a necessary toll for passage can be paid by summing up balances of the cards, only one card can be accessed when the toll is paid. Consequently, the vehicle is stopped due to shortage in toll. The conventional techniques have the problem that the operation may become impossible depending on a state of a recording medium because the operation is executed by accessing the recording medium such as a card.
The technique described in Japanese Patent Laid-open No. 5-210687 has a problem when a card record cannot be read from a card. Thus, an expensive balance in the card becomes useless when the card is damaged, and no operation for reissue can be expected because the record cannot be read.